Articles de revues : « Insect gut symbiosis »

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Takeshita, Kazutaka, et Yoshitomo Kikuchi. « Genomic Comparison of Insect Gut Symbionts from Divergent Burkholderia Subclades ». Genes 11, n^o 7 (3 juillet 2020) : 744. http://dx.doi.org/10.3390/genes11070744.

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Stink bugs of the superfamilies Coreoidea and Lygaeoidea establish gut symbioses with environmentally acquired bacteria of the genus Burkholderia sensu lato. In the genus Burkholderia, the stink bug-associated strains form a monophyletic clade, named stink bug-associated beneficial and environmental (SBE) clade (or Caballeronia). Recently, we revealed that members of the family Largidae of the superfamily Pyrrhocoroidea are associated with Burkholderia but not specifically with the SBE Burkholderia; largid bugs harbor symbionts that belong to a clade of plant-associated group of Burkholderia, called plant-associated beneficial and environmental (PBE) clade (or Paraburkholderia). To understand the genomic features of Burkholderia symbionts of stink bugs, we isolated two symbiotic Burkholderia strains from a bordered plant bug Physopellta gutta (Pyrrhocoroidea: Largidae) and determined their complete genomes. The genome sizes of the insect-associated PBE (iPBE) are 9.5 Mb and 11.2 Mb, both of which are larger than the genomes of the SBE Burkholderia symbionts. A whole-genome comparison between two iPBE symbionts and three SBE symbionts highlighted that all previously reported symbiosis factors are shared and that 282 genes are specifically conserved in the five stink bug symbionts, over one-third of which have unknown function. Among the symbiont-specific genes, about 40 genes formed a cluster in all five symbionts; this suggests a “symbiotic island” in the genome of stink bug-associated Burkholderia.

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Kim, Jiyeun Kate, Dae Woo Son, Chan-Hee Kim, Jae Hyun Cho, Roberta Marchetti, Alba Silipo, Luisa Sturiale et al. « Insect Gut Symbiont Susceptibility to Host Antimicrobial Peptides Caused by Alteration of the Bacterial Cell Envelope ». Journal of Biological Chemistry 290, n^o 34 (26 juin 2015) : 21042–53. http://dx.doi.org/10.1074/jbc.m115.651158.

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The molecular characterization of symbionts is pivotal for understanding the cross-talk between symbionts and hosts. In addition to valuable knowledge obtained from symbiont genomic studies, the biochemical characterization of symbionts is important to fully understand symbiotic interactions. The bean bug (Riptortus pedestris) has been recognized as a useful experimental insect gut symbiosis model system because of its cultivatable Burkholderia symbionts. This system is greatly advantageous because it allows the acquisition of a large quantity of homogeneous symbionts from the host midgut. Using these naïve gut symbionts, it is possible to directly compare in vivo symbiotic cells with in vitro cultured cells using biochemical approaches. With the goal of understanding molecular changes that occur in Burkholderia cells as they adapt to the Riptortus gut environment, we first elucidated that symbiotic Burkholderia cells are highly susceptible to purified Riptortus antimicrobial peptides. In search of the mechanisms of the increased immunosusceptibility of symbionts, we found striking differences in cell envelope structures between cultured and symbiotic Burkholderia cells. The bacterial lipopolysaccharide O antigen was absent from symbiotic cells examined by gel electrophoretic and mass spectrometric analyses, and their membranes were more sensitive to detergent lysis. These changes in the cell envelope were responsible for the increased susceptibility of the Burkholderia symbionts to host innate immunity. Our results suggest that the symbiotic interactions between the Riptortus host and Burkholderia gut symbionts induce bacterial cell envelope changes to achieve successful gut symbiosis.

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Jang, Seonghan, Peter Mergaert, Tsubasa Ohbayashi, Kota Ishigami, Shuji Shigenobu, Hideomi Itoh et Yoshitomo Kikuchi. « Dual oxidase enables insect gut symbiosis by mediating respiratory network formation ». Proceedings of the National Academy of Sciences 118, n^o 10 (1 mars 2021) : e2020922118. http://dx.doi.org/10.1073/pnas.2020922118.

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Most animals harbor a gut microbiota that consists of potentially pathogenic, commensal, and mutualistic microorganisms. Dual oxidase (Duox) is a well described enzyme involved in gut mucosal immunity by the production of reactive oxygen species (ROS) that antagonizes pathogenic bacteria and maintains gut homeostasis in insects. However, despite its nonspecific harmful activity on microorganisms, little is known about the role of Duox in the maintenance of mutualistic gut symbionts. Here we show that, in the bean bug Riptortus pedestris, Duox-dependent ROS did not directly contribute to epithelial immunity in the midgut in response to its mutualistic gut symbiont, Burkholderia insecticola. Instead, we found that the expression of Duox is tracheae-specific and its down-regulation by RNAi results in the loss of dityrosine cross-links in the tracheal protein matrix and a collapse of the respiratory system. We further demonstrated that the establishment of symbiosis is a strong oxygen sink triggering the formation of an extensive network of tracheae enveloping the midgut symbiotic organ as well as other organs, and that tracheal breakdown by Duox RNAi provokes a disruption of the gut symbiosis. Down-regulation of the hypoxia-responsive transcription factor Sima or the regulators of tracheae formation Trachealess and Branchless produces similar phenotypes. Thus, in addition to known roles in immunity and in the formation of dityrosine networks in diverse extracellular matrices, Duox is also a crucial enzyme for tracheal integrity, which is crucial to sustain mutualistic symbionts and gut homeostasis. We expect that this is a conserved function in insects.

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Kim, Jiyeun Kate, Jeong Yun Kwon, Soo Kyoung Kim, Sang Heum Han, Yeo Jin Won, Joon Hee Lee, Chan-Hee Kim, Takema Fukatsu et Bok Luel Lee. « Purine Biosynthesis, Biofilm Formation, and Persistence of an Insect-Microbe Gut Symbiosis ». Applied and Environmental Microbiology 80, n^o 14 (9 mai 2014) : 4374–82. http://dx.doi.org/10.1128/aem.00739-14.

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ABSTRACTTheRiptortus-Burkholderiasymbiotic system is an experimental model system for studying the molecular mechanisms of an insect-microbe gut symbiosis. When the symbiotic midgut ofRiptortus pedestriswas investigated by light and transmission electron microscopy, the lumens of the midgut crypts that harbor colonizingBurkholderiasymbionts were occupied by an extracellular matrix consisting of polysaccharides. This observation prompted us to search for symbiont genes involved in the induction of biofilm formation and to examine whether the biofilms are necessary for the symbiont to establish a successful symbiotic association with the host. To answer these questions, we focused onpurNandpurT, which independently catalyze the same step of bacterial purine biosynthesis. When we disruptedpurNandpurTin theBurkholderiasymbiont, the ΔpurNand ΔpurTmutants grew normally, and only the ΔpurTmutant failed to form biofilms. Notably, the ΔpurTmutant exhibited a significantly lower level of cyclic-di-GMP (c-di-GMP) than the wild type and the ΔpurNmutant, suggesting involvement of the secondary messenger c-di-GMP in the defect of biofilm formation in the ΔpurTmutant, which might operate via impaired purine biosynthesis. The host insects infected with the ΔpurTmutant exhibited a lower infection density, slower growth, and lighter body weight than the host insects infected with the wild type and the ΔpurNmutant. These results show that the function ofpurTof the gut symbiont is important for the persistence of the insect gut symbiont, suggesting the intricate biological relevance of purine biosynthesis, biofilm formation, and symbiosis.

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Singh, Sujata, Archana Singh, Varsha Baweja, Amit Roy, Amrita Chakraborty et Indrakant Kumar Singh. « Molecular Rationale of Insect-Microbes Symbiosis—From Insect Behaviour to Mechanism ». Microorganisms 9, n^o 12 (24 novembre 2021) : 2422. http://dx.doi.org/10.3390/microorganisms9122422.

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Insects nurture a panoply of microbial populations that are often obligatory and exist mutually with their hosts. Symbionts not only impact their host fitness but also shape the trajectory of their phenotype. This co-constructed niche successfully evolved long in the past to mark advanced ecological specialization. The resident microbes regulate insect nutrition by controlling their host plant specialization and immunity. It enhances the host fitness and performance by detoxifying toxins secreted by the predators and abstains them. The profound effect of a microbial population on insect physiology and behaviour is exploited to understand the host–microbial system in diverse taxa. Emergent research of insect-associated microbes has revealed their potential to modulate insect brain functions and, ultimately, control their behaviours, including social interactions. The revelation of the gut microbiota–brain axis has now unravelled insects as a cost-effective potential model to study neurodegenerative disorders and behavioural dysfunctions in humans. This article reviewed our knowledge about the insect–microbial system, an exquisite network of interactions operating between insects and microbes, its mechanistic insight that holds intricate multi-organismal systems in harmony, and its future perspectives. The demystification of molecular networks governing insect–microbial symbiosis will reveal the perplexing behaviours of insects that could be utilized in managing insect pests.

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Koga, Ryuichi, Minoru Moriyama, Naoko Onodera-Tanifuji, Yoshiko Ishii, Hiroki Takai, Masaki Mizutani, Kohei Oguchi et al. « Single mutation makes Escherichia coli an insect mutualist ». Nature Microbiology 7, n^o 8 (4 août 2022) : 1141–50. http://dx.doi.org/10.1038/s41564-022-01179-9.

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AbstractMicroorganisms often live in symbiosis with their hosts, and some are considered mutualists, where all species involved benefit from the interaction. How free-living microorganisms have evolved to become mutualists is unclear. Here we report an experimental system in which non-symbiotic Escherichia coli evolves into an insect mutualist. The stinkbug Plautia stali is typically associated with its essential gut symbiont, Pantoea sp., which colonizes a specialized symbiotic organ. When sterilized newborn nymphs were infected with E. coli rather than Pantoea sp., only a few insects survived, in which E. coli exhibited specific localization to the symbiotic organ and vertical transmission to the offspring. Through transgenerational maintenance with P. stali, several hypermutating E. coli lines independently evolved to support the host’s high adult emergence and improved body colour; these were called ‘mutualistic’ E. coli. These mutants exhibited slower bacterial growth, smaller size, loss of flagellar motility and lack of an extracellular matrix. Transcriptomic and genomic analyses of ‘mutualistic’ E. coli lines revealed independent mutations that disrupted the carbon catabolite repression global transcriptional regulator system. Each mutation reproduced the mutualistic phenotypes when introduced into wild-type E. coli, confirming that single carbon catabolite repression mutations can make E. coli an insect mutualist. These findings provide an experimental system for future work on host–microbe symbioses and may explain why microbial mutualisms are omnipresent in nature.

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Xie, Rongrong, ChenChen Dong, ShengJie Wang, Blessing Danso, Mudasir A. Dar, Radhakrishna S. Pandit, Kiran D. Pawar et al. « Host-Specific Diversity of Culturable Bacteria in the Gut Systems of Fungus-Growing Termites and Their Potential Functions towards Lignocellulose Bioconversion ». Insects 14, n^o 4 (21 avril 2023) : 403. http://dx.doi.org/10.3390/insects14040403.

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Fungus-growing termites are eusocial insects that represent one of the most efficient and unique systems for lignocellulose bioconversion, evolved from a sophisticated symbiosis with lignocellulolytic fungi and gut bacterial communities. Despite a plethora of information generated during the last century, some essential information on gut bacterial profiles and their unique contributions to wood digestion in some fungus-growing termites is still inadequate. Hence, using the culture-dependent approach, the present study aims to assess and compare the diversity of lignocellulose-degrading bacterial symbionts within the gut systems of three fungus-growing termites: Ancistrotermes pakistanicus, Odontotermes longignathus, and Macrotermes sp. A total of 32 bacterial species, belonging to 18 genera and 10 different families, were successfully isolated and identified from three fungus-growing termites using Avicel or xylan as the sole source of carbon. Enterobacteriaceae was the most dominant family represented by 68.1% of the total bacteria, followed by Yersiniaceae (10.6%) and Moraxellaceae (9%). Interestingly, five bacterial genera such as Enterobacter, Citrobacter, Acinetobacter, Trabulsiella, and Kluyvera were common among the tested termites, while the other bacteria demonstrated a termite-specific distribution. Further, the lignocellulolytic potential of selected bacterial strains was tested on agricultural waste to evaluate their capability for lignocellulose bioconversion. The highest substrate degradation was achieved with E. chengduensis MA11 which degraded 45.52% of rice straw. All of the potential strains showed endoglucanase, exoglucanase, and xylanase activities depicting a symbiotic role towards the lignocellulose digestion within the termite gut. The above results indicated that fungus-growing termites harbor a diverse array of bacterial symbionts that differ from species to species, which may play an inevitable role to enhance the degradation efficacy in lignocellulose decomposition. The present study further elaborates our knowledge about the termite-bacteria symbiosis for lignocellulose bioconversion which could be helpful to design a future biorefinery.

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Scharf, Michael E., et Brittany F. Peterson. « A Century of Synergy in Termite Symbiosis Research : Linking the Past with New Genomic Insights ». Annual Review of Entomology 66, n^o 1 (7 janvier 2021) : 23–43. http://dx.doi.org/10.1146/annurev-ento-022420-074746.

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Termites have long been studied for their symbiotic associations with gut microbes. In the late nineteenth century, this relationship was poorly understood and captured the interest of parasitologists such as Joseph Leidy; this research led to that of twentieth-century biologists and entomologists including Cleveland, Hungate, Trager, and Lüscher. Early insights came via microscopy, organismal, and defaunation studies, which led to descriptions of microbes present, descriptions of the roles of symbionts in lignocellulose digestion, and early insights into energy gas utilization by the host termite. Focus then progressed to culture-dependent microbiology and biochemical studies of host–symbiont complementarity, which revealed specific microhabitat requirements for symbionts and noncellulosic mechanisms of symbiosis (e.g., N2 fixation). Today, knowledge on termite symbiosis has accrued exponentially thanks to omic technologies that reveal symbiont identities, functions, and interdependence, as well as intricacies of host–symbiont complementarity. Moving forward, the merging of classical twentieth-century approaches with evolving omic tools should provide even deeper insights into host–symbiont interplay.

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Scharf, Michael E., et Brittany F. Peterson. « A Century of Synergy in Termite Symbiosis Research : Linking the Past with New Genomic Insights ». Annual Review of Entomology 66, n^o 1 (7 janvier 2021) : 23–43. http://dx.doi.org/10.1146/annurev-ento-022420-074746.

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Termites have long been studied for their symbiotic associations with gut microbes. In the late nineteenth century, this relationship was poorly understood and captured the interest of parasitologists such as Joseph Leidy; this research led to that of twentieth-century biologists and entomologists including Cleveland, Hungate, Trager, and Lüscher. Early insights came via microscopy, organismal, and defaunation studies, which led to descriptions of microbes present, descriptions of the roles of symbionts in lignocellulose digestion, and early insights into energy gas utilization by the host termite. Focus then progressed to culture-dependent microbiology and biochemical studies of host–symbiont complementarity, which revealed specific microhabitat requirements for symbionts and noncellulosic mechanisms of symbiosis (e.g., N2 fixation). Today, knowledge on termite symbiosis has accrued exponentially thanks to omic technologies that reveal symbiont identities, functions, and interdependence, as well as intricacies of host–symbiont complementarity. Moving forward, the merging of classical twentieth-century approaches with evolving omic tools should provide even deeper insights into host–symbiont interplay.

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Li, Guannan, Jingjing Sun, Yujie Meng, Chengfeng Yang, Zhuo Chen, Yunfei Wu, Li Tian et al. « The Impact of Environmental Habitats and Diets on the Gut Microbiota Diversity of True Bugs (Hemiptera : Heteroptera) ». Biology 11, n^o 7 (11 juillet 2022) : 1039. http://dx.doi.org/10.3390/biology11071039.

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Insects are generally associated with gut bacterial communities that benefit the hosts with respect to diet digestion, limiting resource supplementation, pathogen defense, and ecological niche expansion. Heteroptera (true bugs) represent one of the largest and most diverse insect lineages and comprise species consuming different diets and inhabiting various ecological niches, even including underwater. However, the bacterial symbiotic associations have been characterized for those basically restricted to herbivorous stink bugs of the infraorder Pentatomomorpha. The gut microbiota associated with the megadiverse heteropteran lineages and the implications of ecological and diet variance remain largely unknown. Here, we conducted a bacterial 16S rRNA amplicon sequencing of the gut microbiota across 30 species of true bugs representative of different ecological niches and diets. It was revealed that Proteobacteria and Firmicute were the predominant bacterial phyla. Environmental habitats and diets synergistically contributed to the diversity of the gut bacterial community of true bugs. True bugs living in aquatic environments harbored multiple bacterial taxa that were not present in their terrestrial counterparts. Carnivorous true bugs possessed distinct gut microbiota compared to phytophagous species. Particularly, assassin bugs of the family Reduviidae possessed a characterized gut microbiota predominantly composed of one Enterococcus with different Proteobacteria, implying a specific association between the gut bacteria and host. Overall, our findings highlight the importance of the comprehensive surveillance of gut microbiota association with true bugs for understanding the molecular mechanisms underpinning insect–bacteria symbiosis.

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Kikuchi, Yoshitomo, Takahiro Hosokawa et Takema Fukatsu. « Specific Developmental Window for Establishment of an Insect-Microbe Gut Symbiosis ». Applied and Environmental Microbiology 77, n^o 12 (29 avril 2011) : 4075–81. http://dx.doi.org/10.1128/aem.00358-11.

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ABSTRACTThe alydid stinkbugRiptortus pedestrisis specifically associated with a beneficialBurkholderiasymbiont in the midgut crypts. Exceptional among insect-microbe mutualistic associations, theBurkholderiasymbiont is not vertically transmitted but orally acquired by nymphal insects from the environment every generation. Here we experimentally investigated the process of symbiont acquisition during the nymphal development ofR. pedestris. In a field population, many 2nd instar nymphs wereBurkholderiafree, while all 3rd, 4th, and 5th instar nymphs were infected. When reared on soil-grown potted soybean plants,Burkholderiaacquisition occurred at a drastically higher frequency in the 2nd instar than in the other instars. Oral administration of culturedBurkholderiacells showed that 2nd and 3rd instar nymphs are significantly more susceptible to the symbiont infection than 1st, 4th, and 5th instar nymphs. Histological observations revealed rudimentary midgut crypts in the 1st instar, in contrast to well-developed midgut crypts in the 2nd and later instars. These results indicate thatR. pedestrisacquires theBurkholderiasymbiont from the environment mainly during the 2nd instar period and strongly suggest that the competence for the symbiont infection is developmentally regulated by the host side. Potential mechanisms involved in infection competence and possible reasons why the infection preferentially occurs in the 2nd instar are discussed.

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Blow, Frances, Anastasia Gioti, Ian B. Goodhead, Maria Kalyva, Anastasia Kampouraki, John Vontas et Alistair C. Darby. « Functional Genomics of a Symbiotic Community : Shared Traits in the Olive Fruit Fly Gut Microbiota ». Genome Biology and Evolution 12, n^o 2 (12 décembre 2019) : 3778–91. http://dx.doi.org/10.1093/gbe/evz258.

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Abstract The olive fruit fly Bactrocera oleae is a major pest of olives worldwide and houses a specialized gut microbiota dominated by the obligate symbiont “Candidatus Erwinia dacicola.” Candidatus Erwinia dacicola is thought to supplement dietary nitrogen to the host, with only indirect evidence for this hypothesis so far. Here, we sought to investigate the contribution of the symbiosis to insect fitness and explore the ecology of the insect gut. For this purpose, we examined the composition of bacterial communities associated with Cretan olive fruit fly populations, and inspected several genomes and one transcriptome assembly. We identified, and reconstructed the genome of, a novel component of the gut microbiota, Tatumella sp. TA1, which is stably associated with Mediterranean olive fruit fly populations. We also reconstructed a number of pathways related to nitrogen assimilation and interactions with the host. The results show that, despite variation in taxa composition of the gut microbial community, core functions related to the symbiosis are maintained. Functional redundancy between different microbial taxa was observed for genes involved in urea hydrolysis. The latter is encoded in the obligate symbiont genome by a conserved urease operon, likely acquired by horizontal gene transfer, based on phylogenetic evidence. A potential underlying mechanism is the action of mobile elements, especially abundant in the Ca. E. dacicola genome. This finding, along with the identification, in the studied genomes, of extracellular surface structure components that may mediate interactions within the gut community, suggest that ongoing and past genetic exchanges between microbes may have shaped the symbiosis.

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Shan, Hongwei, Wei Wu, Zongtao Sun, Jianping Chen et Hongjie Li. « The Gut Microbiota of the Insect Infraorder Pentatomomorpha (Hemiptera : Heteroptera) for the Light of Ecology and Evolution ». Microorganisms 9, n^o 2 (23 février 2021) : 464. http://dx.doi.org/10.3390/microorganisms9020464.

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The stinkbugs of the infraorder Pentatomomorpha are a group of important plant sap-feeding insects, which host diverse microorganisms. Some are located in their complex morphological midgut compartments, while some within the specialized bacteriomes of insect hosts. This perpetuation of symbioses through host generations is reinforced via the diverse routes of vertical transmission or environmental acquisition of the symbionts. These symbiotic partners, reside either through the extracellular associations in midgut or intracellular associations in specialized cells, not only have contributed nutritional benefits to the insect hosts but also shaped their ecological and evolutionary basis. The stinkbugs and gut microbe symbioses present a valuable model that provides insights into symbiotic interactions between agricultural insects and microorganisms and may become potential agents for insect pest management.

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Choi, Okhee, Yeyeong Lee, Byeongsam Kang, Su Kyung Cho, Yongsung Kang, Dong-Wan Kang, Seul-Bi Lee, Sung-Mun Bae et Jinwoo Kim. « Identification and characterization of gut-associated lactic acid bacteria isolated from the bean bug, Riptortus pedestris (Hemiptera : Alydidae) ». PLOS ONE 18, n^o 3 (30 mars 2023) : e0281121. http://dx.doi.org/10.1371/journal.pone.0281121.

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Lactic acid bacteria (LAB) are beneficial bacteria for humans and animals. However, the characteristics and functions of LAB in insects remain unclear. Here, we isolated LAB from the gut of Riptortus pedestris, a pest that is a significant problem in soybean cultivation in Korea, and identified two Lactococcus lactis and one Enterococcus faecalis using matrix-associated laser desorption/ionization-time of flight and 16S rRNA analyses. All three LAB strains survived at pH 8, and L. lactis B103 and E. faecalis B105 survived at pH 9 for 24 h. In addition, these strains survived well in simulated gastric juice of humans containing pepsin and exhibited high resistance to bile salts. Two strains of L. lactis and one of E. faecalis maintained constant density (> 104 colony-forming units [CFU]/mL) at pH 2.5, but viability at pH 2.2 was strain-dependent. The three LAB were reinoculated into second-instar nymphs of R. pedestris and colonized well, reaching a constant density (> 105 CFU/gut) in the adult insect gut. Interestingly, feeding of these LAB increased the survival rate of insects compared to the negative control, with the largest increase seen for L. lactis B103. However, the LAB did not increase the weight or length of adult insects. These results indicate that insect-derived LAB possess the traits required for survival under gastrointestinal conditions and have beneficial effects on insect hosts. The LAB infection frequency of the wild bean bug populations was 89% (n = 18) in Gyeongsangnam-do, South Korea. These LAB can be utilized as a novel probiotic in the cultivation of beneficial insects. This study provides fundamental information about the symbiosis between insects and LAB, and a novel concept for pest control.

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Xu, Yao, Eileen A. Buss et Drion G. Boucias. « Culturing and Characterization of Gut Symbiont Burkholderia spp. from the Southern Chinch Bug, Blissus insularis (Hemiptera : Blissidae) ». Applied and Environmental Microbiology 82, n^o 11 (25 mars 2016) : 3319–30. http://dx.doi.org/10.1128/aem.00367-16.

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ABSTRACTThe phloem-feeding Southern chinch bug,Blissus insularis, harbors a high density of the exocellular bacterial symbiontBurkholderiain the lumen of specialized midgut crypts. Here we developed an organ culture method that initially involved incubating theB. insulariscrypts in osmotically balanced insect cell culture medium. This approach enabled the crypt-inhabitingBurkholderiaspp. to make a transition to anin vitroenvironment and to be subsequently cultured in standard bacteriological media. Examinations using ribotyping and BOX-PCR fingerprinting techniques demonstrated that mostin vitro-produced bacterial cultures were identical to their crypt-inhabitingBurkholderiacounterparts. Genomic and physiological analyses of gut-symbioticBurkholderiaspp. that were isolated individually from two separateB. insularislaboratory colonies revealed that the majority of individual insects harbored a singleBurkholderiaribotype in their midgut crypts, resulting in a diverseBurkholderiacommunity within each colony. The diversity was also exhibited by the phenotypic and genotypic characteristics of theseBurkholderiacultures. Access to cultures of crypt-inhabiting bacteria provides an opportunity to investigate the interaction between symbioticBurkholderiaspp. and theB. insularishost. Furthermore, the culturing method provides an alternative strategy for establishingin vitrocultures of other fastidious insect-associated bacterial symbionts.IMPORTANCEAn organ culture method was developed to establishin vitrocultures of a fastidiousBurkholderiasymbiont associated with the midgut crypts of the Southern chinch bug,Blissus insularis. The identities of the resulting cultures were confirmed using the genomic and physiological features ofBurkholderiacultures isolated fromB. insulariscrypts, showing that host insects maintained the diversity ofBurkholderiaspp. over multiple generations. The availability of characterized gut-symbioticBurkholderiacultures provides a resource for genetic manipulation of these bacteria and for examination of the mechanisms underlying insect-bacterium symbiosis.

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Bowen, David J., Thomas A. Rocheleau, Cathy K. Grutzmacher, Laurence Meslet, Michelle Valens, Daniel Marble, Andrea Dowling, Richard ffrench-Constant et Mark A. Blight. « Genetic and biochemical characterization of PrtA, an RTX-like metalloprotease from Photorhabdus ». Microbiology 149, n^o 6 (1 juin 2003) : 1581–91. http://dx.doi.org/10.1099/mic.0.26171-0.

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Proteases play a key role in the interaction between pathogens and their hosts. The bacterial entomopathogen Photorhabdus lives in symbiosis with nematodes that invade insects. Following entry into the insect, the bacteria are released from the nematode gut into the open blood system of the insect. Here they secrete factors which kill the host and also convert the host tissues into food for the replicating bacteria and nematodes. One of the secreted proteins is PrtA, which is shown here to be a repeats-in-toxin (RTX) alkaline zinc metalloprotease. PrtA has high affinity for artificial substrates such as casein and gelatin and can be inhibited by zinc metalloprotease inhibitors. The metalloprotease also shows a calcium- and temperature-dependent autolysis. The prtA gene carries the characteristic RTX repeated motifs and predicts high similarity to proteases from Erwinia chrysanthemi, Pseudomonas aeruginosa and Serratia marcescens. The prtA gene resides in a locus encoding both the protease ABC transporter (prtBCD) and an intervening ORF encoding a protease inhibitor (inh). PrtA activity is detectable 24 h after artificial bacterial infection of an insect, suggesting that the protease may play a key role in degrading insect tissues rather than in overcoming the insect immune system. Purified PrtA also shows cytotoxicity to mammalian cell cultures, supporting its proposed role in bioconversion of the insect cadaver into food for bacterial and nematode development.

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Setiawan, Ruby, I. Nyoman Sumerta, Syahfitri Anita, Raden Pramesa Narakusumo et Anang Setiawan Achmadi. « Comparison of gut microbiome from Sulawesi carrion and burying beetles (Coleoptera : Silphidae) through metagenomic analysis of 16S rRNA gene ». BIO Web of Conferences 19 (2020) : 00015. http://dx.doi.org/10.1051/bioconf/20201900015.

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Carrion beetle (Coleoptera: Silphidae) is one of the scavengers which obtain nutrition from carcass decomposition which supported by the microbial symbionts through the mutual symbiosis. In this study, we characterized and compared the gut microbial community from the species of Nicrophorinae (Nicrophorus distinctus Grouvelle, 1885) and Silphinae (Necrophila renatae Portevin, 1920) from Dako Mountain, Central Sulawesi using 16S metagenomic approach. A total of 661 bacterial Operational Taxonomic Units (OTUs) at the species level were obtained from the guts of Ni. distinctus and Ne. renatae. Those numbers were predominated by Firmicutes and Proteobacteria, followed by Bacteriodetes in both species. Interestingly, a high number of Lactobacillales was observed in Ni. distinctus and lower number in Clostridiales and Cardiobacteriales compared to Ne. renatae, which showed higher abundance of those classes. Both of these insect species have nearly the same microbial diversity values, even though there some lower taxa levels were found different abundance. These results suggest that the patterns of the gut microbial structure depicted their roles in certain behavior and habitat on decomposing carcasses and could be correlated to the specific level of taxa roles in nutrient processing.

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Jahnes, Benjamin C., et Zakee L. Sabree. « Nutritional symbiosis and ecology of host-gut microbe systems in the Blattodea ». Current Opinion in Insect Science 39 (juin 2020) : 35–41. http://dx.doi.org/10.1016/j.cois.2020.01.001.

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Chen, Shicheng, Ting Yu, Nicolas Terrapon, Bernard Henrissat et Edward D. Walker. « Genome Features of Asaia sp. W12 Isolated from the Mosquito Anopheles stephensi Reveal Symbiotic Traits ». Genes 12, n^o 5 (17 mai 2021) : 752. http://dx.doi.org/10.3390/genes12050752.

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Asaia bacteria commonly comprise part of the microbiome of many mosquito species in the genera Anopheles and Aedes, including important vectors of infectious agents. Their close association with multiple organs and tissues of their mosquito hosts enhances the potential for paratransgenesis for the delivery of antimalaria or antivirus effectors. The molecular mechanisms involved in the interactions between Asaia and mosquito hosts, as well as Asaia and other bacterial members of the mosquito microbiome, remain underexplored. Here, we determined the genome sequence of Asaia strain W12 isolated from Anopheles stephensi mosquitoes, compared it to other Asaia species associated with plants or insects, and investigated the properties of the bacteria relevant to their symbiosis with mosquitoes. The assembled genome of strain W12 had a size of 3.94 MB, the largest among Asaia spp. studied so far. At least 3585 coding sequences were predicted. Insect-associated Asaia carried more glycoside hydrolase (GH)-encoding genes than those isolated from plants, showing their high plant biomass-degrading capacity in the insect gut. W12 had the most predicted regulatory protein components comparatively among the selected Asaia, indicating its capacity to adapt to frequent environmental changes in the mosquito gut. Two complete operons encoding cytochrome bo3-type ubiquinol terminal oxidases (cyoABCD-1 and cyoABCD-2) were found in most Asaia genomes, possibly offering alternative terminal oxidases and allowing the flexible transition of respiratory pathways. Genes involved in the production of 2,3-butandiol and inositol have been found in Asaia sp. W12, possibly contributing to biofilm formation and stress tolerance.

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Liu, Yue, Jia Liu, Xiaopan Zhang et Yueli Yun. « Diversity of Bacteria Associated with Guts and Gonads in Three Spider Species and Potential Transmission Pathways of Microbes within the Same Spider Host ». Insects 14, n^o 10 (29 septembre 2023) : 792. http://dx.doi.org/10.3390/insects14100792.

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Microbial symbiosis plays a crucial role in the ecological and evolutionary processes of animals. It is well known that spiders, with their unique and diverse predatory adaptations, assume an indispensable role in maintaining ecological balance and the food chain. However, our current understanding of spider microbiomes remains relatively limited. The gut microbiota and gonad microbiota of spiders can both potentially influence their physiology, ecology, and behavior, including aspects such as digestion, immunity, reproductive health, and reproductive behavior. In the current study, based on high-throughput sequencing of the 16S rRNA V3 and V4 regions, we detected the gut and gonad microbiota communities of three spider species captured from the same habitat, namely, Eriovixia cavaleriei, Larinioides cornutus, and Pardosa pseudoannulata. In these three species, we observed that, at the phylum level classification, the gut and gonad of E. cavaleriei are primarily composed of Proteobacteria, while those of L. cornutus and P. pseudoannulata are primarily composed of Firmicutes. At the genus level of classification, we identified 372 and 360 genera from the gut and gonad bacterial communities. It is noteworthy that the gut and gonad bacterial flora of E. cavaleriei and L. cornutus were dominated by Wolbachia and Spiroplasma. Results show that there were no differences in microbial communities between females and males of the same spider species. Furthermore, there is similarity between the gut and ovary microbial communities of female spiders, implying a potential avenue for microbial transmission between the gut and gonad within female spiders. By comprehensively studying these two microbial communities, we can establish the theoretical foundation for exploring the relationship between gut and gonad microbiota and their host, as well as the mechanisms through which microbes exert their effects.

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de Vries, E. J., G. Jacobs, M. W. Sabelis, S. B. J. Menken et J. A. J. Breeuwer. « Diet–dependent effects of gut bacteria on their insect host : the symbiosis ofErwiniasp. and western flower thrips ». Proceedings of the Royal Society of London. Series B : Biological Sciences 271, n^o 1553 (22 octobre 2004) : 2171–78. http://dx.doi.org/10.1098/rspb.2004.2817.

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Bennett, H. P. J., et D. J. Clarke. « The pbgPE operon in Photorhabdus luminescens Is Required for Pathogenicity and Symbiosis ». Journal of Bacteriology 187, n^o 1 (1 janvier 2005) : 77–84. http://dx.doi.org/10.1128/jb.187.1.77-84.2005.

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ABSTRACT Photorhabdus is a genus of gram-negative Enterobacteriaceae that is pathogenic to insect larvae while also maintaining a mutualistic relationship with nematodes from the family Heterorhabditis, where the bacteria occupy the gut of the infective juvenile (IJ) stage of the nematode. In this study we describe the identification and characterization of a mutation in the pbgE1 gene of Photorhabdus luminescens TT01, predicted to be the fifth gene in the pbgPE operon. We show that this mutant, BMM305, is strongly attenuated in virulence against larvae of the greater wax moth, Galleria mellonella, and we report that BMM305 is more sensitive to the cationic antimicrobial peptide, polymyxin B, and growth in mildly acidic pH than the parental strain of P. luminescens. Moreover, we also show that the lipopolysaccharide (LPS) present on the surface of BMM305 does not appear to contain any O antigen. Complementation studies reveal that the increased sensitivity to polymyxin B and growth in mildly acidic pH can be rescued by the in trans expression of pbgE1, while the defects in O-antigen assembly and pathogenicity require the in trans expression of pbgE1 and the downstream genes pbgE2 and pbgE3. Finally, we show that BMM305 is defective in symbiosis as this mutant is unable to colonize the gut of the IJ stage of the nematode. Therefore, we conclude that the pbgPE operon is required for both pathogenicity and symbiosis in P. luminescens.

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Ffrench-Constant, Richard H., Nicholas Waterfield, Valerie Burland, Nicole T. Perna, Phillip J. Daborn, David Bowen et Frederick R. Blattner. « A Genomic Sample Sequence of the Entomopathogenic Bacterium Photorhabdus luminescens W14 : Potential Implications for Virulence ». Applied and Environmental Microbiology 66, n^o 8 (1 août 2000) : 3310–29. http://dx.doi.org/10.1128/aem.66.8.3310-3329.2000.

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ABSTRACT Photorhabdus luminescens is a pathogenic bacterium that lives in the guts of insect-pathogenic nematodes. After invasion of an insect host by a nematode, bacteria are released from the nematode gut and help kill the insect, in which both the bacteria and the nematodes subsequently replicate. However, the bacterial virulence factors associated with this “symbiosis of pathogens” remain largely obscure. In order to identify genes encoding potential virulence factors, we performed ∼2,000 random sequencing reads from a P. luminescens W14 genomic library. We then compared the sequences obtained to sequences in existing gene databases and to theEscherichia coli K-12 genome sequence. Here we describe the different classes of potential virulence factors found. These factors include genes that putatively encode Tc insecticidal toxin complexes, Rtx-like toxins, proteases and lipases, colicin and pyocins, and various antibiotics. They also include a diverse array of secretion (e.g., type III), iron uptake, and lipopolysaccharide production systems. We speculate on the potential functions of each of these gene classes in insect infection and also examine the extent to which the invertebrate pathogen P. luminescens shares potential antivertebrate virulence factors. The implications for understanding both the biology of this insect pathogen and links between the evolution of vertebrate virulence factors and the evolution of invertebrate virulence factors are discussed.

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Husnik, Filip, Vaclav Hypsa et Alistair Darby. « Insect—Symbiont Gene Expression in the Midgut Bacteriocytes of a Blood-Sucking Parasite ». Genome Biology and Evolution 12, n^o 4 (18 février 2020) : 429–42. http://dx.doi.org/10.1093/gbe/evaa032.

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Abstract Animals interact with a diverse array of both beneficial and detrimental microorganisms. In insects, these symbioses in many cases allow feeding on nutritionally unbalanced diets. It is, however, still not clear how are obligate symbioses maintained at the cellular level for up to several hundred million years. Exact mechanisms driving host–symbiont interactions are only understood for a handful of model species and data on blood-feeding hosts with intracellular bacteria are particularly scarce. Here, we analyzed interactions between an obligately blood-sucking parasite of sheep, the louse fly Melophagus ovinus, and its obligate endosymbiont, Arsenophonus melophagi. We assembled a reference transcriptome for the insect host and used dual RNA-Seq with five biological replicates to compare expression in the midgut cells specialized for housing symbiotic bacteria (bacteriocytes) to the rest of the gut (foregut–hindgut). We found strong evidence for the importance of zinc in the system likely caused by symbionts using zinc-dependent proteases when acquiring amino acids, and for different immunity mechanisms controlling the symbionts than in closely related tsetse flies. Our results show that cellular and nutritional interactions between this blood-sucking insect and its symbionts are less intimate than what was previously found in most plant-sap sucking insects. This finding is likely interconnected to several features observed in symbionts in blood-sucking arthropods, particularly their midgut intracellular localization, intracytoplasmic presence, less severe genome reduction, and relatively recent associations caused by frequent evolutionary losses and replacements.

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Li, Jiale, Ningning Fu, Ming Wang, Chenglong Gao, Bingtao Gao, Lili Ren, Jing Tao et Youqing Luo. « Functional and Compositional Changes in Sirex noctilio Gut Microbiome in Different Habitats : Unraveling the Complexity of Invasive Adaptation ». International Journal of Molecular Sciences 25, n^o 5 (21 février 2024) : 2526. http://dx.doi.org/10.3390/ijms25052526.

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The mutualistic symbiosis relationship between the gut microbiome and their insect hosts has attracted much scientific attention. The native woodwasp, Sirex nitobei, and the invasive European woodwasp, Sirex noctilio, are two pests that infest pines in northeastern China. Following its encounter with the native species, however, there is a lack of research on whether the gut microbiome of S. noctilio changed, what causes contributed to these alterations, and whether these changes were more conducive to invasive colonization. We used high-throughput and metatranscriptomic sequencing to investigate S. noctilio larval gut and frass from four sites where only S. noctilio and both two Sirex species and investigated the effects of environmental factors, biological interactions, and ecological processes on S. noctilio gut microbial community assembly. Amplicon sequencing of two Sirex species revealed differential patterns of bacterial and fungal composition and functional prediction. S. noctilio larval gut bacterial and fungal diversity was essentially higher in coexistence sites than in separate existence sites, and most of the larval gut bacterial and fungal community functional predictions were significantly different as well. Moreover, temperature and precipitation positively correlate with most of the highly abundant bacterial and fungal genera. Source-tracking analysis showed that S. noctilio larvae at coexistence sites remain dependent on adult gut transmission (vertical transmission) or recruitment to frass (horizontal transmission). Meanwhile, stochastic processes of drift and dispersal limitation also have important impacts on the assembly of S. noctilio larval gut microbiome, especially at coexistence sites. In summary, our results reveal the potential role of changes in S. noctilio larval gut microbiome in the successful colonization and better adaptation of the environment.

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Zhang, Xiancui, Fan Zhang et Xingmeng Lu. « Diversity and Functional Roles of the Gut Microbiota in Lepidopteran Insects ». Microorganisms 10, n^o 6 (16 juin 2022) : 1234. http://dx.doi.org/10.3390/microorganisms10061234.

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Lepidopteran insects are one of the most widespread and speciose lineages on Earth, with many common pests and beneficial insect species. The evolutionary success of their diversification depends on the essential functions of gut microorganisms. This diverse gut microbiota of lepidopteran insects provides benefits in nutrition and reproductive regulation and plays an important role in the defence against pathogens, enhancing host immune homeostasis. In addition, gut symbionts have shown promising applications in the development of novel tools for biological control, biodegradation of waste, and blocking the transmission of insect-borne diseases. Even though most microbial symbionts are unculturable, the rapidly expanding catalogue of microbial genomes and the application of modern genetic techniques offer a viable alternative for studying these microbes. Here, we discuss the gut structure and microbial diversity of lepidopteran insects, as well as advances in the understanding of symbiotic relationships and interactions between hosts and symbionts. Furthermore, we provide an overview of the function of the gut microbiota, including in host nutrition and metabolism, immune defence, and potential mechanisms of detoxification. Due to the relevance of lepidopteran pests in agricultural production, it can be expected that the research on the interactions between lepidopteran insects and their gut microbiota will be used for biological pest control and protection of beneficial insects in the future.

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Gonella, Elena, et Alberto Alma. « The Role of Symbiont-Targeted Strategies in the Management of Pentatomidae and Tephritidae Pests under an Integrated Vision ». Agronomy 13, n^o 3 (16 mars 2023) : 868. http://dx.doi.org/10.3390/agronomy13030868.

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The interaction between insects and gut bacterial symbionts is, nowadays, regarded as an important element in the implementation of pest management, in consideration of the urgent need for sustainable alternatives to insecticide use. In this framework, a major tool is symbiotic control, with the main ready-to-use application represented by the interruption of obligate symbioses. Two insect families, namely Pentatomidae in the Hemiptera order and Tephritidae in Diptera, have been indicated as outstanding targets for symbiont-oriented control tactics. An important advantage of interrupting obligate symbioses is the target shift from insect to bacteria, which avoids insecticide use; however, the compatibility between this approach and other pest/disease management strategies is crucial to design low-impact pest control programs. Here we present the state of knowledge regarding the integration of symbiont manipulation in sustainable plant protection plans. Research assessing the potential for multitarget applications is reported, as well as studies on the impact of symbiont interruption on nontarget species. Besides symbiont-targeted pest control, another relevant outcome of symbiont manipulation is the restoration of microbial perturbation in mass-reared insects used in pest control programs, which is a required step to allow the success of other tactics, such as the Sterile Insect Technique. Despite the potential contribution that symbiont-targeted strategies may offer to integrated pest management, we point out that operational caveats may emerge in symbiont-oriented control in relation to the target extension on the label directions and to the number of required treatments. Future work is needed to increase the target range and the number of tested formulations exploiting the interruption of bacterial symbioses. This will also require assessment of the effect of different products on beneficial organisms, including biological control agents. Finally, the authorization of formulates for symbiotic control should be taken into consideration by the regulatory bodies, to really promote new readily available control options.

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Mondal, Sankhadeep, Jigyasa Somani, Somnath Roy, Azariah Babu et Abhay K. Pandey. « Insect Microbial Symbionts : Ecology, Interactions, and Biological Significance ». Microorganisms 11, n^o 11 (30 octobre 2023) : 2665. http://dx.doi.org/10.3390/microorganisms11112665.

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The guts of insect pests are typical habitats for microbial colonization and the presence of bacterial species inside the gut confers several potential advantages to the insects. These gut bacteria are located symbiotically inside the digestive tracts of insects and help in food digestion, phytotoxin breakdown, and pesticide detoxification. Different shapes and chemical assets of insect gastrointestinal tracts have a significant impact on the structure and makeup of the microbial population. The number of microbial communities inside the gastrointestinal system differs owing to the varying shape and chemical composition of digestive tracts. Due to their short generation times and rapid evolutionary rates, insect gut bacteria can develop numerous metabolic pathways and can adapt to diverse ecological niches. In addition, despite hindering insecticide management programs, they still have several biotechnological uses, including industrial, clinical, and environmental uses. This review discusses the prevalent bacterial species associated with insect guts, their mode of symbiotic interaction, their role in insecticide resistance, and various other biological significance, along with knowledge gaps and future perspectives. The practical consequences of the gut microbiome and its interaction with the insect host may lead to encountering the mechanisms behind the evolution of pesticide resistance in insects.

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Kashkouli, Marzieh, Yaghoub Fathipour et Mohammad Mehrabadi. « Heritable Gammaproteobacterial Symbiont Improves the Fitness of Brachynema germari Kolenati (Hemiptera : Pentatomidae) ». Environmental Entomology 48, n^o 5 (30 juillet 2019) : 1079–87. http://dx.doi.org/10.1093/ee/nvz089.

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Abstract The pistachio green stink bug, Brachynema germari Kolenati, is an abundant and economic insect pest in most pistachio-growing regions. Some physiological and ecological features of this pest have been studied, but the microbiological nature of symbiotic bacteria and biological aspects of this host–symbiont interaction have been poorly understood. In the present study, we explored the host-associated environment, phylogeny, and acquisition features of the bacterial symbiont of the insect. Furthermore, the importance of the symbiont on the biological (i.e., lifespan, stage composition, and body weight) and behavioral characteristics (i.e., resting/wandering behaviors of the newborn nymphs) of the host were investigated. We found that a rod-shaped gammaproteobacterium was persistently colonized the fourth midgut region of the insect. Molecular phylogenetic and fluorescence in situ hybridization analyses strongly suggest that this symbiont should be placed in the genus Pantoea of the Enterobacteriales. Egg surface sterilization resulted in the aposymbiotic insects suggesting the vertical transmission of symbiont via egg surface smearing upon oviposition. Symbiotic and aposymbiotic B. germari showed no significant differences in the wandering behaviors of the first nymphal stages, whereas the symbiont-free insects exhibited retarded growth, lower longevity, and adult body weight. Taken together, these data provide a better understanding of the relationship between the bacterial symbiont and B. germari and demonstrate that the insect is heavily affected by the deprival of its gut symbionts.

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Kim, Jiyeun Kate, Na Hyang Kim, Ho Am Jang, Yoshitomo Kikuchi, Chan-Hee Kim, Takema Fukatsu et Bok Luel Lee. « Specific Midgut Region Controlling the Symbiont Population in an Insect-Microbe Gut Symbiotic Association ». Applied and Environmental Microbiology 79, n^o 23 (13 septembre 2013) : 7229–33. http://dx.doi.org/10.1128/aem.02152-13.

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ABSTRACTMany insects possess symbiotic bacteria that affect the biology of the host. The level of the symbiont population in the host is a pivotal factor that modulates the biological outcome of the symbiotic association. Hence, the symbiont population should be maintained at a proper level by the host's control mechanisms. Several mechanisms for controlling intracellular symbionts of insects have been reported, while mechanisms for controlling extracellular gut symbionts of insects are poorly understood. The bean bugRiptortus pedestrisharbors a betaproteobacterial extracellular symbiont of the genusBurkholderiain the midgut symbiotic organ designated the M4 region. We found that the M4B region, which is directly connected to the M4 region, also harborsBurkholderiasymbiont cells, but the symbionts therein are mostly dead. A series of experiments demonstrated that the M4B region exhibits antimicrobial activity, and the antimicrobial activity is specifically potent against theBurkholderiasymbiont but not the culturedBurkholderiaand other bacteria. The antimicrobial activity of the M4B region was detected in symbiotic host insects, reaching its highest point at the fifth instar, but not in aposymbiotic host insects, which suggests the possibility of symbiont-mediated induction of the antimicrobial activity. This antimicrobial activity was not associated with upregulation of antimicrobial peptides of the host. Based on these results, we propose that the M4B region is a specialized gut region ofR. pedestristhat plays a critical role in controlling the population of theBurkholderiagut symbiont. The molecular basis of the antimicrobial activity is of great interest and deserves future study.

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Nencioni, Anita, Roberta Pastorelli, Gaia Bigiotti, Maria Alexandra Cucu et Patrizia Sacchetti. « Diversity of the Bacterial Community Associated with Hindgut, Malpighian Tubules, and Foam of Nymphs of Two Spittlebug Species (Hemiptera : Aphrophoridae) ». Microorganisms 11, n^o 2 (13 février 2023) : 466. http://dx.doi.org/10.3390/microorganisms11020466.

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Spittlebugs are xylem-sap feeding insects that can exploit a nutrient-poor diet, thanks to mutualistic endosymbionts residing in various organs of their body. Although obligate symbioses in some spittlebug species have been quite well studied, little is known about their facultative endosymbionts, especially those inhabiting the gut. Recently, the role played by spittlebugs as vectors of the phytopathogenetic bacterium Xylella fastidiosa aroused attention to this insect group, boosting investigations aimed at developing effective yet sustainable control strategies. Since spittlebug nymphs are currently the main target of applied control, the composition of gut bacterial community of the juveniles of Philaenus spumarius and Lepyronia coleoptrata was investigated using molecular techniques. Moreover, bacteria associated with their froth, sampled from different host plants, were studied. Results revealed that Sodalis and Rickettsia bacteria are the predominant taxa in the gut of P. spumarius and L. coleoptrata nymphs, respectively, while Rhodococcus was found in both species. Our investigations also highlighted the presence of recurring bacteria in the froth. Furthermore, the foam hosted several bacterial species depending on the host plant, the insect species, or on soil contaminant. Overall, first findings showed that nymphs harbor a large and diverse bacterial community in their gut and froth, providing new accounts to the knowledge on facultative symbionts of spittlebugs.

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Nováková, Eva, Filip Husník, Eva Šochová et Václav Hypša. « Arsenophonus and Sodalis Symbionts in Louse Flies : an Analogy to the Wigglesworthia and Sodalis System in Tsetse Flies ». Applied and Environmental Microbiology 81, n^o 18 (6 juillet 2015) : 6189–99. http://dx.doi.org/10.1128/aem.01487-15.

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ABSTRACTSymbiosis between insects and bacteria result in a variety of arrangements, genomic modifications, and metabolic interconnections. Here, we present genomic, phylogenetic, and morphological characteristics of a symbiotic system associated withMelophagus ovinus, a member of the blood-feeding family Hippoboscidae. The system comprises four unrelated bacteria representing different stages in symbiosis evolution, from typical obligate mutualists inhabiting bacteriomes to freely associated commensals and parasites. Interestingly, the whole system provides a remarkable analogy to the association betweenGlossinaand its symbiotic bacteria. In both, the symbiotic systems are composed of an obligate symbiont and two facultative intracellular associates,SodalisandWolbachia. In addition, extracellularBartonellaresides in the gut ofMelophagus. However, the phylogenetic origins of the two obligate mutualist symbionts differ. InGlossina, the mutualisticWigglesworthiaappears to be a relatively isolated symbiotic lineage, whereas inMelophagus, the obligate symbiont originated within the widely distributedArsenophonuscluster. Although phylogenetically distant, the two obligate symbionts display several remarkably similar traits (e.g., transmission via the host's “milk glands” or similar pattern of genome reduction). To obtain better insight into the biology and possible role of theM. ovinusobligate symbiont, “CandidatusArsenophonus melophagi,” we performed several comparisons of its gene content based on assignments of the Cluster of Orthologous Genes (COG). Using this criterion, we show that within a set of 44 primary and secondary symbionts, “Ca. Arsenophonus melophagi” is most similar toWigglesworthia. On the other hand, these two bacteria also display interesting differences, such as absence of flagellar genes inArsenophonusand their presence inWigglesworthia. This finding implies that a flagellum is not essential for bacterial transmission via milk glands.

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Salem, Hassan, Eugen Bauer, Anja S. Strauss, Heiko Vogel, Manja Marz et Martin Kaltenpoth. « Vitamin supplementation by gut symbionts ensures metabolic homeostasis in an insect host ». Proceedings of the Royal Society B : Biological Sciences 281, n^o 1796 (7 décembre 2014) : 20141838. http://dx.doi.org/10.1098/rspb.2014.1838.

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Despite the demonstrated functional importance of gut microbes, our understanding of how animals regulate their metabolism in response to nutritionally beneficial symbionts remains limited. Here, we elucidate the functional importance of the African cotton stainer's ( Dysdercus fasciatus ) association with two actinobacterial gut symbionts and subsequently examine the insect's transcriptional response following symbiont elimination. In line with bioassays demonstrating the symbionts' contribution towards host fitness through the supplementation of B vitamins, comparative transcriptomic analyses of genes involved in import and processing of B vitamins revealed an upregulation of gene expression in aposymbiotic (symbiont-free) compared with symbiotic individuals; an expression pattern that is indicative of B vitamin deficiency in animals. Normal expression levels of these genes, however, can be restored by either artificial supplementation of B vitamins into the insect's diet or reinfection with the actinobacterial symbionts. Furthermore, the functional characterization of the differentially expressed thiamine transporter 2 through heterologous expression in Xenopus laevis oocytes confirms its role in cellular uptake of vitamin B1. These findings demonstrate that despite an extracellular localization, beneficial gut microbes can be integral to the host's metabolic homeostasis, reminiscent of bacteriome-localized intracellular mutualists.

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Noman, M. S., L. Liu, Z. Bai et Z. Li. « Tephritidae bacterial symbionts : potentials for pest management ». Bulletin of Entomological Research 110, n^o 1 (21 juin 2019) : 1–14. http://dx.doi.org/10.1017/s0007485319000403.

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AbstractTephritidae is a large family that includes several fruit and vegetable pests. These organisms usually harbor a variegated bacterial community in their digestive systems. Symbiotic associations of bacteria and fruit flies have been well-studied in the generaAnastrepha, Bactrocera, Ceratitis,andRhagoletis.Molecular and culture-based techniques indicate that many genera of the Enterobacteriaceae family, especially the genera ofKlebsiella, Enterobacter, Pectobacterium, Citrobacter, Erwinia,andProvidenciaconstitute the most prevalent populations in the gut of fruit flies. The function of symbiotic bacteria provides a promising strategy for the biological control of insect pests. Gut bacteria can be used for controlling fruit fly through many ways, including attracting as odors, enhancing the success of sterile insect technique, declining the pesticide resistance, mass rearing of parasitoids and so on. New technology and recent research improved our knowledge of the gut bacteria diversity and function, which increased their potential for pest management. In this review, we discussed the diversity of bacteria in the economically important fruit fly and the use of these bacteria for controlling fruit fly populations. All the information is important for strengthening the future research of new strategies developed for insect pest control by the understanding of symbiotic relationships and multitrophic interactions between host plant and insects.

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Zheng, Xiang, Qidi Zhu, Zhijun Zhou, Fangtong Wu, Lixuan Chen, Qianrong Cao et Fuming Shi. « Gut bacterial communities across 12 Ensifera (Orthoptera) at different feeding habits and its prediction for the insect with contrasting feeding habits ». PLOS ONE 16, n^o 4 (26 avril 2021) : e0250675. http://dx.doi.org/10.1371/journal.pone.0250675.

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Insect microbial symbioses play a critical role in insect lifecycle, and insect gut microbiome could be influenced by many factors. Studies have shown that host diet and taxonomy have a strong influence on insect gut microbial community. In this study, we performed sequencing of V3-V4 region of 16S rRNA gene to compare the composition and diversity of 12 Ensifera from 6 provinces of China. Moreover, the influences of feeding habits and taxonomic status of insects on their gut bacterial community were evaluated, which might provide reference for further application research. The results showed that Proteobacteria (45.66%), Firmicutes (34.25%) and Cyanobacteria (7.7%) were the predominant bacterial phyla in Ensifera. Moreover, the gut bacterial community composition of samples with different feeding habits was significantly different, which was irrespective of their taxa. The highest diversity of gut bacteria was found in the omnivorous Ensifera. Furthermore, common and unique bacteria with biomarkers were found based on the dietary characteristics of the samples. However, the bacterial community structure of the Ensifera samples was significantly different from that of Caelifera. Therefore, we concluded that feeding habits and taxonomic status jointly affect the gut bacterial community composition of the samples from Orthoptera. However, the influence of feeding habit dominates when taxonomy category below the suborder level. In addition, the dominant, common and unique bacterial community structure could be used to predict the contrastic feeding habits of insects belonging to Ensifera.

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Jaruseranee, Nanthanit, et Somboon Kamtaeja. « Caffeine Concentration Effects on Gut Microbiota of the Coffee Berry Borer (Hypothenemus hampei Ferrari) and Possible Links to Insect Pest Control ». Trends in Sciences 20, n^o 12 (10 septembre 2023) : 7050. http://dx.doi.org/10.48048/tis.2023.7050.

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Coffee Berry Borer (CBB) is a significant coffee pest worldwide. This includes Thailand. The arabica coffee plantations in Chiang Rai province, northern Thailand, have experienced significant economic losses as a consequence of this insect. The purpose of this study was to investigate changes in the gut bacterial community in response to caffeine concentrations in the growing environment, which may have implications for coffee pest insect control. A total of 38 species of gut microbiota were grown in non-caffeine conditions. On average, 14.5 ± 1.8 species were found in all 6 sampling sites. In caffeine conditions, the number of culturable gut bacteria was significantly decreased to 18 species with an average species abundance of 7.2 ± 3.1. The results revealed that Pseudomonas fulva and P. punonensis were caffeine-tolerant species that displayed significant growth at 20 mM caffeine concentration. The findings of this study will contribute to a better understanding of gut microbiota in CBBs and its potential application for coffee insect pest control, as well as valuable information on organic coffee from northern Thailand. HIGHLIGHTS Coffee Berry Borer, or CBB, (Hypothenemus hampei Ferrari; Coleoptera: Scolytidae), is the most serious coffee pest worldwide. This pest has evolved to be caffeine resistant, allowing it to survive and reproduce inside coffee fruits. Caffeine is an alkaloid found in coffee (genus Coffea), and comprises a chemical defense mechanism to protect against insect pests. It is critical for preventing pest outbreaks in Coffea and other commercial plants. Next generation sequencing of 16S rRNA was used to estimate the taxonomic abundance of CBB's gut microbiome, which has a symbiotic relationship with the insects. The gut bacterial community discovered in this study included at least 37 Proteobacteria species and 1 Bacteroidetes species. This study examined the effect of caffeine on the diversity of bacterial symbionts in the gut of CBBs. Gut bacterial diversity and abundance were significantly reduced in media containing 20 mM caffeine. GRAPHICAL ABSTRACT

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Somerville, Jasmine, Liqin Zhou et Ben Raymond. « Aseptic Rearing and Infection with Gut Bacteria Improve the Fitness of Transgenic Diamondback Moth, Plutella xylostella ». Insects 10, n^o 4 (28 mars 2019) : 89. http://dx.doi.org/10.3390/insects10040089.

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Mass insect rearing can have a range of applications, for example in biological control of pests. The competitive fitness of released insects is extremely important in a number of applications. Here, we investigated how to improve the fitness of a transgenic diamondback moth, which has shown variation in mating ability when reared in different insectaries. Specifically we tested whether infection with a gut bacteria, Enterobacter cloacae, and aseptic rearing of larvae could improve insect growth and male performance. All larvae were readily infected with E. cloacae. Under aseptic rearing, pupal weights were reduced and there was a marginal reduction in larval survival. However, aseptic rearing substantially improved the fitness of transgenic males. In addition, under aseptic rearing, inoculation with E. cloacae increased pupal weights and male fitness, increasing the proportion of transgenic progeny from 20% to 30% relative to uninfected insects. Aseptic conditions may improve the fitness of transgenic males by excluding microbial contaminants, while symbiont inoculation could further improve fitness by providing additional protection against infection, or by normalizing insect physiology. The simple innovation of incorporating antibiotic into diet, and inoculating insects with symbiotic bacteria that are resistant to that antibiotic, could provide a readily transferable tool for other insect rearing systems.

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Caspi-Fluger, A., M. Inbar, S. Steinberg, Y. Friedmann, M. Freund, N. Mozes-Daube et E. Zchori-Fein. « Characterization of the symbiontRickettsiain the mirid bugNesidiocoris tenuis(Reuter) (Heteroptera : Miridae) ». Bulletin of Entomological Research 104, n^o 6 (25 juillet 2014) : 681–88. http://dx.doi.org/10.1017/s0007485314000492.

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AbstractNesidiocoris tenuis(Reuter) (Heteroptera: Miridae) is an omnivorous insect used for biological control. Augmentative release and conservation ofN. tenuishave been used for pest control in tomato crops. Intracellular bacterial symbionts of arthropods are common in nature and have diverse effects on their hosts; in some cases they can dramatically affect biological control. Fingerprinting methods showed that the symbiotic complex associated withN. tenuisincludesWolbachiaandRickettsia. RickettsiaofN. tenuiswas further characterized by sequencing the16S rRNAandgltAbacterial genes, measuring its amount in different developmental stages of the insect by real-time polymerase chain reaction, and localizing the bacteria in the insect's body by fluorescencein situhybridization. TheRickettsiainN. tenuisexhibited 99 and 96% similarity of both sequenced genes toRickettsia belliiandRickettsiareported fromBemisia tabaci, respectively. The highest amount ofRickettsiawas measured in the 5th instar and adult, and the symbionts could be detected in the host gut and ovaries. Although the role played byRickettsiain the biology ofN. tenuisis currently unknown, their high amount in the adults and localization in the gut suggest that they may have a nutritional role in this insect.

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Fukatsu, Takema, et Takahiro Hosokawa. « Capsule-Transmitted Gut Symbiotic Bacterium of the Japanese Common Plataspid Stinkbug, Megacopta punctatissima ». Applied and Environmental Microbiology 68, n^o 1 (janvier 2002) : 389–96. http://dx.doi.org/10.1128/aem.68.1.389-396.2002.

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ABSTRACT The Japanese common plataspid stinkbug, Megacopta punctatissima, deposits small brown particles, or symbiont capsules, on the underside of the egg mass for the purpose of transmission of symbiotic bacteria to the offspring. We investigated the microbiological aspects of the bacteria contained in the capsule, such as microbial diversity, phylogenetic placement, localization in vivo, and fitness effects on the host insect. Restriction fragment length polymorphism analysis of 16S ribosomal DNA clones revealed that a single bacterial species dominates the microbiota in the capsule. The bacterium was not detected in the eggs but in the capsules, which unequivocally demonstrated that the bacterium is transmitted to the offspring of the insect orally rather than transovarially, through probing of the capsule content. Molecular phylogenetic analysis showed that the bacterium belongs to the γ-subdivision of the Proteobacteria. In adult insects the bacterium was localized in the posterior section of the midgut. Deprivation of the bacterium from the nymphs resulted in retarded development, arrested growth, abnormal body coloration, and other symptoms, suggesting that the bacterium is essential for normal development and growth of the host insect.

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Morgan-Richards, Mary, Craig J. Marshall, Patrick J. Biggs et Steven A. Trewick. « Insect Freeze-Tolerance Downunder : The Microbial Connection ». Insects 14, n^o 1 (13 janvier 2023) : 89. http://dx.doi.org/10.3390/insects14010089.

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Insects that are freeze-tolerant start freezing at high sub-zero temperatures and produce small ice crystals. They do this using ice-nucleating agents that facilitate intercellular ice growth and prevent formation of large crystals where they can damage tissues. In Aotearoa/New Zealand the majority of cold adapted invertebrates studied survive freezing at any time of year, with ice formation beginning in the rich microbiome of the gut. Some freeze-tolerant insects are known to host symbiotic bacteria and/or fungi that produce ice-nucleating agents and we speculate that gut microbes of many New Zealand insects may provide ice-nucleating active compounds that moderate freezing. We consider too the possibility that evolutionary disparate freeze-tolerant insect species share gut microbes that are a source of ice-nucleating agents and so we describe potential transmission pathways of shared gut fauna. Despite more than 30 years of research into the freeze-tolerant mechanisms of Southern Hemisphere insects, the role of exogenous ice-nucleating agents has been neglected. Key traits of three New Zealand freeze-tolerant lineages are considered in light of the supercooling point (temperature of ice crystal formation) of microbial ice-nucleating particles, the initiation site of freezing, and the implications for invertebrate parasites. We outline approaches that could be used to investigate potential sources of ice-nucleating agents in freeze-tolerant insects and the tools employed to study insect microbiomes.

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Skowronek, Marcin, Ewa Sajnaga, Małgorzata Pleszczyńska, Waldemar Kazimierczak, Magdalena Lis et Adrian Wiater. « Bacteria from the Midgut of Common Cockchafer (Melolontha melolontha L.) Larvae Exhibiting Antagonistic Activity Against Bacterial Symbionts of Entomopathogenic Nematodes : Isolation and Molecular Identification ». International Journal of Molecular Sciences 21, n^o 2 (16 janvier 2020) : 580. http://dx.doi.org/10.3390/ijms21020580.

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The mechanisms of action of the complex including entomopathogenic nematodes of the genera Steinernema and Heterorhabditis and their mutualistic partners, i.e., bacteria Xenorhabdus and Photorhabdus, have been well explained, and the nematodes have been commercialized as biological control agents against many soil insect pests. However, little is known regarding the nature of the relationships between these bacteria and the gut microbiota of infected insects. In the present study, 900 bacterial isolates that were obtained from the midgut samples of Melolontha melolontha larvae were screened for their antagonistic activity against the selected species of the genera Xenorhabdus and Photorhabdus. Twelve strains exhibited significant antibacterial activity in the applied tests. They were identified based on 16S rRNA and rpoB, rpoD, or recA gene sequences as Pseudomonas chlororaphis, Citrobacter murliniae, Acinetobacter calcoaceticus, Chryseobacterium lathyri, Chryseobacterium sp., Serratia liquefaciens, and Serratia sp. The culture filtrate of the isolate P. chlororaphis MMC3 L3 04 exerted the strongest inhibitory effect on the tested bacteria. The results of the preliminary study that are presented here, which focused on interactions between the insect gut microbiota and mutualistic bacteria of entomopathogenic nematodes, show that bacteria inhabiting the gut of insects might play a key role in insect resistance to entomopathogenic nematode pressure.

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Huang, Qiuyan, Yilu Feng, Hong-Wei Shan, Jian-Ping Chen et Wei Wu. « A Novel Nitrogen-Fixing Bacterium Raoultella electrica Isolated from the Midgut of the Leafhopper Recilia dorsalis ». Insects 14, n^o 5 (30 avril 2023) : 431. http://dx.doi.org/10.3390/insects14050431.

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Nitrogen is a crucial element for the growth and development of insects, but herbivorous insects often suffer from nitrogen nutrition deficiencies in their diets. Some symbiotic microorganisms can provide insect hosts with nitrogen nutrition through nitrogen fixation. Extensive research has clearly demonstrated the process of nitrogen fixation by symbiotic microorganisms in termites, while evidence supporting the occurrence and significance of nitrogen fixation in the diets of the Hemiptera is less conclusive. In this study, we isolated a strain of R. electrica from the digestive tract of a leafhopper, R. dorsalis, and found that it had nitrogen-fixing capabilities. Fluorescence in situ hybridization results showed that it was located in the gut of the leafhopper. Genome sequencing revealed that R. electrica possessed all the genes required for nitrogen fixation. We further evaluated the growth rate of R. electrica in nitrogen-containing and nitrogen-free media and measured its nitrogenase activity through an acetylene reduction assay. The findings of these studies could shed light on how gut microbes contribute to our understanding of nitrogen fixation.

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Kwong, Waldan K., Amanda L. Mancenido et Nancy A. Moran. « Immune system stimulation by the native gut microbiota of honey bees ». Royal Society Open Science 4, n^o 2 (février 2017) : 170003. http://dx.doi.org/10.1098/rsos.170003.

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Gut microbial communities can greatly affect host health by modulating the host's immune system. For many important insects, however, the relationship between the gut microbiota and immune function remains poorly understood. Here, we test whether the gut microbial symbionts of the honey bee can induce expression of antimicrobial peptides (AMPs), a crucial component of insect innate immunity. We find that bees up-regulate gene expression of the AMPs apidaecin and hymenoptaecin in gut tissue when the microbiota is present. Using targeted proteomics, we detected apidaecin in both the gut lumen and the haemolymph; higher apidaecin concentrations were found in bees harbouring the normal gut microbiota than in bees lacking gut microbiota. In in vitro assays, cultured strains of the microbiota showed variable susceptibility to honey bee AMPs, although many seem to possess elevated resistance compared to Escherichia coli . In some trials, colonization by normal gut symbionts resulted in improved survivorship following injection with E. coli . Our results show that the native, non-pathogenic gut flora induces immune responses in the bee host. Such responses might be a host mechanism to regulate the microbiota, and could potentially benefit host health by priming the immune system against future pathogenic infections.

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Kaiwa, Nahomi, Takahiro Hosokawa, Yoshitomo Kikuchi, Naruo Nikoh, Xian Ying Meng, Nobutada Kimura, Motomi Ito et Takema Fukatsu. « Primary Gut Symbiont and Secondary, Sodalis-Allied Symbiont of the Scutellerid Stinkbug Cantao ocellatus ». Applied and Environmental Microbiology 76, n^o 11 (16 avril 2010) : 3486–94. http://dx.doi.org/10.1128/aem.00421-10.

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ABSTRACT Symbiotic associations with midgut bacteria have been commonly found in diverse phytophagous heteropteran groups, where microbiological characterization of the symbiotic bacteria has been restricted to the stinkbug families Acanthosomatidae, Plataspidae, Pentatomidae, Alydidae, and Pyrrhocoridae. Here we investigated the midgut bacterial symbiont of Cantao ocellatus, a stinkbug of the family Scutelleridae. A specific gammaproteobacterium was consistently identified from the insects of different geographic origins. The bacterium was detected in all 116 insects collected from 9 natural host populations. Phylogenetic analyses revealed that the bacterium constitutes a distinct lineage in the Gammaproteobacteria, not closely related to gut symbionts of other stinkbugs. Diagnostic PCR and in situ hybridization demonstrated that the bacterium is extracellularly located in the midgut 4th section with crypts. Electron microscopy of the crypts revealed a peculiar histological configuration at the host-symbiont interface. Egg sterilization experiments confirmed that the bacterium is vertically transmitted to stinkbug nymphs via egg surface contamination. In addition to the gut symbiont, some individuals of C. ocellatus harbored another bacterial symbiont in their gonads, which was closely related to Sodalis glossinidius, the secondary endosymbiont of tsetse flies. Biological aspects of the primary gut symbiont and the secondary Sodalis-allied symbiont are discussed.

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BAJYA, D. R., DEEPIKA ARYA, M. RANJITH, M. C. LAKHARAN et S. K. RAZA. « Isolation and identification of cellulose demoting symbionts from gut of subterranean termite, Odontotermes obesus ». Indian Journal of Agricultural Sciences 85, n^o 7 (9 juillet 2015) : 970–72. http://dx.doi.org/10.56093/ijas.v85i7.50142.

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The study was carried out to isolate and identify the symbionts, viz. cellulose demoting bacteria and fungus in termite gut. The experiment was conducted during (February 2013- July 2013) at biotechnology laboratory, Institute of Pesticide Formulation Technology, Gurgaon (Haryana). Termites are wood eating insects and are among the most important ligno cellulose- digesting insects and possess a variety of symbiotic microorganisms in their gut. Nutrient agar, potato dextrose and Carboxy Methyl Cellulose (CMC) were used to isolate the dry bacterial strain and fungus. The cellulose is demoted in termite gut by the production of cellulase enzyme which is detected by Congo red stain. Colony morphology and staining technique such as Gram's staining, Congo red staining and oxidase test for bacterial strain gave an idea for the presence of genera Citrobacter and Enterobacter. Aspergillus nidulans has been isolated and identified at division of plant pathology, IARI, New Delhi. These bacteria and fungus were able to assimilate CMC which aid in digestion of cellulose in subterranean termite Odontotermes obesus (Rambur) and this study abetted to understand more about the symbionts associated with digestive mechanism of termites.

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Kikuchi, Yoshitomo, Takahiro Hosokawa et Takema Fukatsu. « Insect-Microbe Mutualism without Vertical Transmission : a Stinkbug Acquires a Beneficial Gut Symbiont from the Environment Every Generation ». Applied and Environmental Microbiology 73, n^o 13 (4 mai 2007) : 4308–16. http://dx.doi.org/10.1128/aem.00067-07.

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ABSTRACT The broad-headed bug Riptortus clavatus (Heteroptera: Alydidae) possesses a number of crypts at a posterior midgut region, which house a dense population of a bacterial symbiont belonging to the genus Burkholderia. Although the symbiont is highly prevalent (95 to 100%) in the host populations, the symbiont phylogeny did not reflect the host systematics at all. In order to understand the mechanisms underlying the promiscuous host-symbiont relationship despite the specific and prevalent association, we investigated the transmission mode and the fitness effects of the Burkholderia symbiont in R. clavatus. Inspection of eggs and a series of rearing experiments revealed that the symbiont is not vertically transmitted but is environmentally acquired by nymphal insects. The Burkholderia symbiont was present in the soil of the insect habitat, and a culture strain of the symbiont was successfully isolated from the insect midgut. Rearing experiments by using sterilized soybean bottles demonstrated that the cultured symbiont is able to establish a normal and efficient infection in the host insect, and the symbiont infection significantly improves the host fitness. These results indicated that R. clavatus postnatally acquires symbiont of a beneficial nature from the environment every generation, uncovering a previously unknown pathway through which a highly specific insect-microbe association is maintained. We suggest that the stinkbug-Burkholderia relationship may be regarded as an insect analogue of the well-known symbioses between plants and soil-associated microbes, such as legume-Rhizobium and alder-Frankia relationships, and we discuss the evolutionary relevance of the mutualistic but promiscuous insect-microbe association.

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Ikuze, Edith, Stephanie Cromwell, Paul Ayayee et Joe Louis. « Influence of Microbes in Mediating Sorghum Resistance to Sugarcane Aphids ». Diversity 16, n^o 2 (27 janvier 2024) : 85. http://dx.doi.org/10.3390/d16020085.

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Gut microbiomes profoundly influence insect health and mediate interactions between plant hosts and their environments. Insects, including aphids, harbour diverse obligate symbionts that synthesize essential nutrients and facultative symbionts that enhance host fitness in specific ecological contexts. Sorghum (Sorghum bicolor) is a significant cereal crop cultivated worldwide that has been negatively affected by the presence of an invasive piercing-sucking insect pest, the sugarcane aphid (SCA; Melanaphis sacchari). We previously identified SC265 and SC1345 as the resistant and susceptible sorghum lines, respectively, among the founder nested association mapping (NAM) population. Here, using these resistant and susceptible lines, we explored variations in the SCA gut microbiome when they feed on two different sorghum lines with varied resistance levels. Analyses after excluding the obligate endosymbiont Buchnera aphidicola from the dataset showed a significant difference in microbial diversity and composition between resistant and susceptible sorghum lines 7- and 14 days post aphid infestation. Our results indicate that the SCA fed on susceptible and resistant sorghum lines had Pseudomonadaceae and Rhizobiaceae, respectively, as the most abundant bacterial families. Differences in gut microbial community composition were underscored by alpha diversity metrics and beta diversity compositional analyses. These findings contribute to our understanding of the intricate interplay between plant and aphid microbiomes, shedding light on potential avenues to bolster sorghum resistance to SCA.

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Sharma, Kritika. « Silkworm Gut Microflora as a Source : Biotechnological Applications ». Asian Journal of Biology 20, n^o 9 (5 septembre 2024) : 30–46. http://dx.doi.org/10.9734/ajob/2024/v20i9436.

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The term "microflora" has gained popularity as researchers explore the symbiotic relationships between microorganisms and their hosts, from our skin to our gut. Insects, including the silkworm, have mutualistic ties with their gut microflora, making them a valuable resource for studying essential molecules. The silkworm, with its rapid generation time, abundant genetic resources, well-defined genetic background, and numerous homologous genes, is an ideal model organism for various life science studies. Silkworm rearing is simple, inexpensive, and does not require ethical clearance, allowing the gut microflora of Bombyx mori to be harnessed for biotechnological applications. Silkworm gut microbes can synthesize and produce extracellular enzymes, such as cellulases, proteases, and lipases, which are crucial for industries ranging from biofuel production to waste management and textile processing. Additionally, these microbes can produce vitamins, such as vitamin B12, and metabolites like short-chain fatty acids (SCFAs), which have potential applications in the food and pharmaceutical industries. Antimicrobial substances produced by the gut microflora, including bacteriocins and lactic acid, are of particular therapeutic importance, offering natural alternatives to traditional antibiotics and contributing to the development of novel antimicrobial therapies. Moreover, the antioxidants generated by these symbionts, such as glutathione and superoxide dismutase (SOD), have significant implications for health supplements and cosmetics, owing to their ability to combat oxidative stress and support immune function. Beyond their metabolic capacities, silkworm symbionts can be used to enhance health, target and manage agricultural pests, and control vectors of human diseases in an environmentally friendly manner. Recent research has also highlighted the potential of mutualistic symbiotic bacteria for plastic disposal, with enzymes like PETases showing promise in degrading synthetic polymers. Despite extensive knowledge on the biology and physiology of the silkworm Bombyx mori, few studies have focused on its gut microflora. Modern genetic techniques, such as the genetic transformation of silkworms with genes of interest, may help overcome these research gaps. Increasing research efforts on silkworm gut microflora will not only reveal new symbiotic relationships but also identify new sources of biotechnologically important molecules and enzymes for therapeutic and industrial applications.

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González-Román, Pilar, Diana Hernández-Oaxaca, Rafael Bustamante-Brito, Marco A. Rogel et Esperanza Martínez-Romero. « On the Origins of Symbiotic Fungi in Carmine Cochineals and Their Function in the Digestion of Plant Polysaccharides ». Insects 15, n^o 10 (9 octobre 2024) : 783. http://dx.doi.org/10.3390/insects15100783.

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The cochineal insect Dactylopius coccus Costa (Hemiptera) has cultural and economic value because it produces carminic acid that is used commercially. In this study, distinct fungi were cultured from dissected tissue and identified as Penicillium, Coniochaeta, Arthrinium, Cladosporium, Microascus, Aspergillus, and Periconia. Fungi were microscopically observed inside cochineals in the gut, fat body, and ovaries. Since cochineals spend their lives attached to cactus leaves and use the sap as feed, they can obtain fungi from cacti plants. Indeed, we obtained Penicillium, Aspergillus, and Cladosporium fungi from cacti that were identical to those inside cochineals, supporting their plant origin. Fungi could be responsible for the degrading activities in the insect guts, since cellulase, pectinase, and amylase enzymatic activities in insect guts decreased in fungicide-treated cochineals. Our findings set the basis for the further study of the interactions between insects, fungi, and their host plants.

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Nicoletti, Rosario, Elia Russo et Andrea Becchimanzi. « Cladosporium—Insect Relationships ». Journal of Fungi 10, n^o 1 (19 janvier 2024) : 78. http://dx.doi.org/10.3390/jof10010078.

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The range of interactions between Cladosporium, a ubiquitous fungal genus, and insects, a class including about 60% of the animal species, is extremely diverse. The broad case history of antagonism and mutualism connecting Cladosporium and insects is reviewed in this paper based on the examination of the available literature. Certain strains establish direct interactions with pests or beneficial insects or indirectly influence them through their endophytic development in plants. Entomopathogenicity is often connected to the production of toxic secondary metabolites, although there is a case where these compounds have been reported to favor pollinator attraction, suggesting an important role in angiosperm reproduction. Other relationships include mycophagy, which, on the other hand, may reflect an ecological advantage for these extremely adaptable fungi using insects as carriers for spreading in the environment. Several Cladosporium species colonize insect structures, such as galleries of ambrosia beetles, leaf rolls of attelabid weevils and galls formed by cecidomyid midges, playing a still uncertain symbiotic role. Finally, the occurrence of Cladosporium in the gut of several insect species has intriguing implications for pest management, also considering that some strains have proven to be able to degrade insecticides. These interactions especially deserve further investigation to understand the impact of these fungi on pest control measures and strategies to preserve beneficial insects.

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